In areas where it is hot and dry such as the American Southwest, the evaporation of water from spas, swimming pools and fountains (hereinafter collectively referred to as pools) tends to cause increases in the level of total dissolved solids in the water. Chemicals have been used to attempt to control TDS unsuccessfully.
The increased levels of total dissolved solids tend to require the use of even greater amounts of chemical agents to control the scaling and staining of the walls of the pool and for clarity of the pool water. Further for commercial units such as municipal or hotel pools, human use also contributes to an increase in TDS.
In addition to the use of chemical agents, it is a typical practice to periodically empty and refill the pool because of the buildup of TDS. Disposal of drained pools, such as a 20,000 gallon pool, are, in most instances done by draining the pool to storm sewer systems or into the street or other convenient location. This is not only wasteful of an important natural resource, water, but also can strain municipal storm sewer treatment systems and contributes to the degradation of the infrastructure such as concrete, streets, curbs, pipes and gradings due to the chemical agents and high total dissolved solids in the drain water.
For example, in a municipality with 10,000 pools holding an average of 20,000 gallons per pool would amount to 200,000,000 gallons of water disposed of per year by emptying pools.
In an unrelated system, some homes or businesses have evaporative coolers for air conditioning purposes. The water not evaporated during the evaporative process for cooling, is discharged as waste. A typical example would be an evaporative cooler which discharges an average of 6 gallons of waste water per hour for ten hours per day. At 68 cooling days per year, that equals 4080 gallons of water per year per cooler which is treated as a nuisance and discharged.
There is a need to conserve the water heretofore discharged into storm sewer systems or otherwise treated as a nuisance. There is also a need for a system which can control the TDS levels in pools to maintain the clarity, reduce scaling and staining and avoid the expense of cleaning and draining and to further reduce the amount of chemical additives required for the pool.